Many medical departments are nowadays increasingly organized according to disease rather than to modality. A reason for this is that, e.g., in the case of cardiology, no single cardiac imaging modality exists which gives all the relevant information. Information from Computed Tomography (CT), Magnetic Resonance (MR), Ultrasound, and other image modalities is therefore increasingly combined. This combining of information may involve displaying medical images from different image modalities side-by-side, fusing them, or otherwise combining information from several medical images. To facilitate the combining, the medical images may be mutually aligned. Such image alignment is also referred to as image registration, and typically involves determining a transformation between the different coordinate systems associated with the medical images, and subsequently using the transformation to compensate for any misalignment between the medical images.
It is known to align medical images based on anatomical landmarks. For example, US 2013/0094738 A1 describes a method and apparatus for aligning two sets of medical imaging data. The first and second sets of image data are obtained respectively, using first and second different medical imaging modalities, of an anatomical feature of a subject. For each set, an axis of the anatomical feature and a landmark point for the anatomical feature is determined. For example, the anatomical feature may be the left ventricle of the heart, and the landmark may be the apex of the left ventricle. The first and second sets are then aligned by comparing the respective axes and landmark points.
A problem of the alignment of US 2013/0094738 A1 is that it is insufficiently flexible to deal with differences between the two sets of medical imaging data.